<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="https://cdn.jsdelivr.net/npm/vue@2.7.10/dist/vue.min.js"></script>
</head>

<body>
    <div id="app">
        商品：<input type="text" v-model="name"><br> 数量：
        <input type="text" v-model="count"><br> 价格：
        <input type="text" v-model="price"><br>
        <button @click="add">添加到购物车</button>
        <hr>
        <ul>
            <li v-for="item in list" v-text="item.name+'的数量是'+
            item.count+',单价是'+item.price+',小计：'+item.sum"></li>
            <li>总计：总数----{{sumcount}} 总价---{{tosum}}</li>
        </ul>
    </div>
</body>
<script>
    var vue = new Vue({
        el: '#app',
        data: {
            name: '',
            count: '',
            price: '',
            sum: 0,
            list: [{
                name: '牙刷',
                count: 5,
                price: 10,
                sum: 50
            }, {
                name: '牙膏',
                count: 2,
                price: 20,
                sum: 40
            }, {
                name: '镜子',
                count: 3,
                price: 30,
                sum: 90
            }]
        },
        methods: {
            add() {
                this.sum = this.count * this.price
                var goods = {
                    name: this.name,
                    count: this.count,
                    price: this.price,
                    sum: this.sum
                }
                this.list.push(goods)
                this.name = ''
                this.count = ''
                this.price = ''
            }
        },
        computed: {
            sumcount() {
                return this.list.reduce((total, b) => {
                    return total + Number(b.count)
                }, 0)
            },
            tosum() {
                return this.list.reduce((total, b) => {
                    return total + Number(b.sum)
                }, 0)
            }
        }
    })
</script>

</html>